In some types of multi-stage axial flow turbo machines, the stator blades are fixedly mounted in the stator housing by locking the tangs, or journals, at the outer ends of the blades to the stator housing. In large high speed machines, the stator blades are subjected to forces of substantial magnitude tending to create a vibratory condition in the blades. To reduce such vibration, inner shroud rings have been fixedly secured to the inner ends of the fixed blades: for example, as shown in U.S. Pat. No. 3,269,701, assigned to the assignee herein.
In turbo machines for certain applications, it is desirable to mount at least one row of the stator blades for rotative adjustment about their lengthwise axis. To eliminate excessive vibration in the adjustable blades, it is necessary to provide a relatively close running fit between the blade journals and stator housing and the inner shroud ring. In view of the mounting of the blades for rotation, problems are encountered in the manufacture and assembly of the inner shroud rings to the blades to provide the proper support thereof, and to provide free adjustment of the blades under operating conditions.
This invention has as an object a stator blade assembly structure wherein the inner shroud ring is of simple one-piece construction, economical to manufacture and which is quickly and conveniently mounted on the inner ends of an arcuate series of stator blades.